Lotus Elan

Strombergs v. Webers Advice please

PostPost by: tyasman » Mon Mar 03, 2008 9:23 am

I am about to buy a baby Elan. My last one was a '68 S4 Sprint with big valve head and Webers. I am advised against getting one with Strombergs as there is a big performance difference. Is this true? Will I get a Sprint spec. with Strombergs? Are Dellortos as good as Webers or should I insist on the latter? I don't drive really fast, just wanting pokey overtaking acceleration up to about 80mph
Thanks to all for replies
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PostPost by: steveww » Mon Mar 03, 2008 9:54 am

You have opened a can of worms here :wink:

Dellortos have better progression than the Webers. Both of these carbs will give you maximum power as the Weber head ultimately flows better than the Stromberg head. The Strombergs give a better torque curve and the smoothest transistion not to mention better gas mileage. IMHO the Strombergs are better for a road car and the Webers for a race care.

Nomex anyone :twisted:
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PostPost by: nebogipfel » Mon Mar 03, 2008 12:43 pm

If you find a good car at a good price on Strombergs, buy it.

That said, I'd probably go for a Weber/Dellorto car. I've never really liked Strombergs on anything

A Weber or Dellorto car will always have the edge .....and sound lovely :D

Chapman flirted with Strommies to meet US emissions not because he thought they were better.

I agree about the can of worms ........ I probably just poked them with a stick :lol:
John

No longer active on here, I value my privacy.
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PostPost by: andrewdmoore » Mon Mar 03, 2008 12:58 pm

Hi,

Checkout this excellent new website. Reading the 'Sprint differences' page leads me to believe that Sprints were never issued with Strombergs. Mine has got one of the bonnets referred to with a bulge which is great for looking straight down when you're driving, but thankfully I've got Dellortos under the bonnet.

Regards, Andrew

http://www.lotuselansprint.com/index.asp?pageid=41823
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PostPost by: MintSprint » Mon Mar 03, 2008 1:18 pm

My last Elan was on Strombergs, my current car is on Dellortos.

As Steve says, the Strombergs give a better torque curve in standard tune than the Weber/Dellorto cars, but they're not so easily tunable (realistic limit is about 130bhp, compared to an easy, tractable 145bhp for a Weber/Dellorto Big Valve).

The Strombergs are undoubtably more economical.

The most significant downsides for the Strombergs though, are:
1) Carburettor icing; in cool, damp weather this was a real problem, I found.
2) Parts; I had my Strombergs rebuilt by a specialist and I understand that it's getting very tricky to get hold of replacement parts in some instances. With Webers, you can (at a price) buy a completely new set of carbs off the shelf.
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PostPost by: elan_fan » Mon Mar 03, 2008 1:22 pm

Ok got a few days off and I'm waiting for the paint to dry on some skirting in the bathroom, got quite a job list from the boss but hopefully if I crack on I should have a few days in the garage. Anyway here is my take on the subject.
Divide the Stromberg issue into a couple of chunks, the Stromberg equiped cars that went to north America are well down on power compared to weber equiped cars and require a fair bit of work removing the emmision throttles and crossover pipes then finding a 40953 dizzy etc. However if you are considering a car built for the home market I would not say there is a great deal of difference, the Stromberg SE has D profile cams and a factory "ported" head and the 40953 dizzy gives a bit more early advance all adding up to a quite powerful motor. Downside of Stroms is inferior quality of idle, Icing in cold weather, the "look" and of course less bragging rights to the un educated. Weber cars idle better, and to most eyes look the part.
Chapman put Stroms on for nothing other than cost. I have a weber equiped +2S and a Stromberg equiped S4 SE. When i bought the S4 the carb type was not a consideration and both cars sound great, in fact the S4 has a genuine Lotus Exhaust, and after the baffles blew out (about 50 miles) it sounds great.
The Strom SE pulls a 3.55 rear axle and the Sprint pulls a 3.77 and that accounts for some of the performance deficit though it's not much.

Right, worms stirred up a bit, back to my skirting. :roll:
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PostPost by: steveww » Mon Mar 03, 2008 5:55 pm

Just one minor correction on a previous post.

All spares and brand new Strombergs are available from www.burlen.co.uk

Icing in cold damp conditions is a known issue with the Strombergs however as I only drive mine in the summer I have never experienced the problem even in the English summer weather. :wink:

I think when buying an old Elan there is more to worry about that what carbs are fitted. Rusty sub frame anyone?
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PostPost by: MintSprint » Mon Mar 03, 2008 7:06 pm

steveww wrote:Just one minor correction on a previous post.

All spares and brand new Strombergs are available from www.burlen.co.uk


Until you actually try to order them, that is. :wink:

It was Burlen who rebuilt the carbs on my Stromberg Elan. I was advised at the time that if there was wear in certain components, the carbs would be scrap and I'd have no alternative but to try to find a good second-hand pair from somewhere else. I understand (from Burlen) that there were several different models of 175CD Stromberg and the type used on the UK Elan is not one of the common variants.

Click on the 'Zenith' tab on Burlen's website and you'll find that the range of spares is actually rather limited and they don't list new carbs at all.

Click the 'SU Conversion' tab and you'll see why; their solution is to replace Strombergs CD series carburettors with SU's. Unfortunately, they don't list a conversion kit for the Stromberg Elan (it is possible to convert to SU's, but not straightforward and, of course, not original).

One further point of advice for the original poster: if you do decide to go for a Stromberg equipped car, make sure the carbs haven't been over-tightened, as it's easy to distort the carb mounting flanges if you do.
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PostPost by: denicholls2 » Mon Mar 03, 2008 11:24 pm

Webers = 1 throat per cylinder :D
Strombergs = not. Cylinders are also improperly paired for delivery of a consistent mixture to each cylinder in a pair.

Where I disagree is about the "not straightforward" part of exchanging Strombergs and SUs. There may be minor linkage differences, but numerous cars of the era bolted on one or the other over time. I think you'll find the same to be true if you investigate the two designs.

SUs and Strombergs are basically the same concept, and SUs do seem to have a more loyal following.

Note that much of the power difference between Federal and home-market cars was not inherent to the carburetor choice but to related emissions tuning that doesn't have to be duplicated.

For drivability and especially economy, Stromberg or SU.
For coolness and ultimate power output (and potentially longer life between rebuilds based on mixture consistency), Weber or Dellorto.
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PostPost by: Elanintheforest » Tue Mar 04, 2008 10:43 am

Here?s a totally non-technical view, from a bloke who?s had weber twinks for 30 years.

Last year, on this forum, I bought a 1970 S4 dhc with Strombergs?it was yellow so I had to have it. Before I got it home I was on eBay and phoning various contacts looking for a Weber head and a pair of 40s?.and found a nice set at the right price.

I got the car home and thought I?d take it for a spin before replacing those nasty carbs and compromised head. What a delight! It starts instantly, pulls cleanly through the range and it?s fast?I certainly can?t tell any difference on the road between a Weber car and a Stromberg car. On the S4 you won?t miss the weber noise either?the exhaust is so loud you can?t hear anything else.

So she?s staying with Strombergs. As an added bonus, I then looked on eBay for a spare cylinder head and carbs?and within 2 weeks bought a mint head and pair of carbs for ?140?.about ?600 LESS that you?d pay for a weber head and pair of 40s, if you can find a decent set.

I?m not justifying my purchase in any way?I still have a few Weber engined Elans. But experiencing the two has wiped away years of prejudice and pub-talk. Doesn?t Miles Wilkins also claim that the S/E Stromberg engine was the fastest of the standard twincams?

Just another view?.

Mark
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PostPost by: tyasman » Tue Mar 04, 2008 1:07 pm

Thanks everyone. Fascinating stuff and has given me enough info to decide what I want. (Keeping it secret though)
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PostPost by: MintSprint » Tue Mar 04, 2008 1:23 pm

denicholls2 wrote:Where I disagree is about the "not straightforward" part of exchanging Strombergs and SUs. There may be minor linkage differences, but numerous cars of the era bolted on one or the other over time. I think you'll find the same to be true if you investigate the two designs.


I've not done the conversion myself, so if you have I'll defer to your better knowledge, but when I researched it as an alternative to rebuilding the Strombergs on my car, three potential issues were identified:
1) Clearance; the dashpots on SU's are taller than those on the Strombergs and can apparently foul the bonnet bulge on Elans.
2) Needle profiles; if you read the chapter on the Stromberg engine in Miles Wilkins, you'll see that the mixture took a bit of getting right, even for Lotus, and the SU conversion is no different. Even with the work that Lotus did, the Stromberg engines have a reputation for a slightly uneven 'hunting' idle, and it takes a bit of experimentation to get to a needle profile that works equally well on the SUs.
3) Ignition profile; again, if you read Miles Wilkins, you'll see that the ignition advance on the Stromberg engine is a bit of a compromise, and the SU responds differently and has different needs again. Unless you get mappable ignition, chances are your ignition advance profile will end up a bit of a compromise based on a bit of a compromise!

Nothing that can't be sorted, but I don't think it's as simple as bolting a pair of SU's on, fitting XYZ needle profile, and off you go...

Having said all which, I'd echo Mark's comments: my Stromberg S4 was perfectly tractable, torquey and quick, and I certainly wouldn't rule out a car simply because it was on Strombergs.

In particular, the 'not as free revving as Weber' comment you frequently see is a red herring; because the Stromberg is a variable choke design with a damped piston, the throttle response certainly isn't as crisp as Webers/Dellortos if you are simply sitting on your driveway blipping the throttle (being damped, the choke lags slightly behind the throttle opening), but in actual driving it doesn't make any difference, basically because the car can't out-accelerate the carburettor response.

But given two equally good cars, for equal price, most people would take the Weber/Dellorto option over the Strombergs.
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PostPost by: hatman » Wed Mar 05, 2008 9:43 am

Elanintheforest wrote: ...experiencing the two has wiped away years of prejudice and pub-talk.


Some time ago I was out in the Elan and called at a Triumph Stag garage/workshop/restorer. The proprietor started talking to me about the Lotus and I happened to mention something along the lines of 'fortunately it's got the Dell 'Ortos rather than those bloomin' Strombergs that Lotus had to fit to meet US emission laws'.

It transpired that Stags have Strombergs and the chap was only too pleased to correct me with regard to the Strommies' all round excellence - an opinion based on years of experience, rather than my own knowledge base, ie never having owned any Stromberg-equipped car and having a vague recollection of having read something about them at one time and, in any case, every one knows that they're crap, don't they? Oops! :oops:
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PostPost by: ppnelan » Thu Mar 06, 2008 9:10 am

A Stromberg engine CAN be, er, rubbish if the carbs are not working properly (I speak from experience), but when everything is working as it should they are TERRIFIC! (I speak from experience again!).
With current UK fuel prices, there's a good reason to avoid the fashionable 'pour-in-a-shed-load-of-fuel' Webers and Dellortos (which are a little better?)... :lol:

:arrow: Matthew
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PostPost by: saildrive2001 » Thu Mar 06, 2008 8:55 pm

Read Miles Wilkins book & he states that the highest HP they saw from a stock engine was the SE spec with UK Strombergs. Guess what I have on my car? In the past I have used my car in the winter here in SW Ontario & providing you keep the engine temp I had very few icing problems. I did have all but a 2inch width of the nose intake blanked off. For summer use it has never been a problem. Strombergs are the modern version of the SU carb so why would you go back in technology?
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